Method, apparatus, and electronic device having living body detection capability

Abstract

A method of living body detection includes: capturing a plurality of images of an object under test by using an image sensor; calculating variations of brightness values of pixel units of the plurality of images; and, determining whether the object under test is a living body according to the variations.

What is claimed is: 
     
         1 . A method of living body detection, comprising:
 capturing a plurality of images of an object under test by using an image sensor;   calculating variations of brightness values of pixel units of the plurality of images; and   determining whether the object under test is a living body according to the variations.   
     
     
         2 . The method of  claim 1 , wherein the calculating step comprises:
 for a particular spatial position in the plurality of images:
 deriving a variation of brightness values of two pixel units corresponding to the particular spatial position respectively in any two adjacent images among the plurality of images, the deriving step being sequentially performed for pixel units corresponding to the particular spatial position respectively in each group of two adjacent images among the plurality of images to generate variations associated with the particular spatial position; and 
 accumulating and averaging the variations associated with the particular spatial position to calculate an average as a variation indicator for the particular spatial position. 
   
     
     
         3 . The method of  claim 1 , wherein the calculating step comprises:
 for a particular spatial position in the plurality of images:
 performing standard deviation calculation upon pixel units corresponding to the particular spatial position in the plurality of images to calculate multiple deviation values for the particular spatial position; and 
 accumulating and averaging the multiple deviation values to calculate an average as a variation for the particular spatial position; 
   wherein the calculating step is sequentially performed for each spatial position one by one to calculate the variations of the brightness values of the pixel units.   
     
     
         4 . The method of  claim 1 , further comprising:
 employing a speckle contrast filter upon the plurality of images to generate a plurality of processed images;   wherein the calculating step is performed based on the plurality of processed images to calculate the variations of the brightness values of the pixel units.   
     
     
         5 . The method of  claim 1 , wherein one of the pixel units comprises a single one pixel or a plurality of pixels. 
     
     
         6 . The method of  claim 1 , wherein the determining step comprises:
 comparing the variations with a specific threshold to determine whether the object under test is a living body.   
     
     
         7 . The method of  claim 6 , wherein the comparing step comprises:
 determining that the object under test is the living body when a number of variations corresponding to higher values is higher than the specific threshold; and   determining that the object under test is a non-living body when the number is lower than the specific threshold.   
     
     
         8 . An apparatus having living body detection capability, comprising:
 an image sensor, configured for capturing a plurality of images of an object under test; and   a processor, coupled to the image sensor, configured for calculating variations of brightness values of pixel units of the plurality of images, and for determining whether the object under test is a living body according to the variations.   
     
     
         9 . The apparatus of  claim 8 , wherein the processor is configured for:
 for a particular spatial position in the plurality of images:
 deriving a variation of brightness values of two pixel units corresponding to the particular spatial position respectively in any two adjacent images among the plurality of images, wherein the deriving step is sequentially performed for pixel units corresponding to the particular spatial position respectively in each group of two adjacent images among the plurality of images to generate variations associated with the particular spatial position; and 
 accumulating and averaging the variations associated with the particular spatial position to calculate an average as a variation indicator for the particular spatial position. 
   
     
     
         10 . The apparatus of  claim 8 , wherein the processor is configured for:
 for a particular spatial position in the plurality of images:
 performing standard deviation calculation upon pixel units corresponding to the particular spatial position in the plurality of images to calculate multiple deviation values for the particular spatial position; and 
 accumulating and averaging the multiple deviation values to calculate an average as a variation for the particular spatial position; 
 wherein the processor is arranged to sequentially perform the standard deviation calculation and the accumulating and averaging for each spatial position one by one to calculate the variations of the brightness values of the pixel units. 
   
     
     
         11 . The apparatus of  claim 8 , further comprising:
 a speckle contrast filter circuit, coupled to processor, configured for performing a speckle contrast calculation upon the plurality of images to generate a plurality of processed images;   wherein the processor is arranged to calculate the variations of the brightness values of the pixel units based on the plurality of processed images.   
     
     
         12 . The apparatus of  claim 8 , wherein one of the pixel units comprises a single one pixel or a plurality of pixels. 
     
     
         13 . The apparatus of  claim 8 , wherein the processor is arranged for comparing the variations with a specific threshold to determine whether the object under test is a living body. 
     
     
         14 . The apparatus of  claim 13 , wherein the processor is arranged for:
 determining that the object under test is the living body when a number of variations corresponding to higher values is higher than the specific threshold; and   determining that the object under test is a non-living body when the number is lower than the specific threshold.   
     
     
         15 . An electronic device, comprising:
 a physiological feature detection circuit;   an image sensor, configured for capturing a plurality of images of an object under test; and   a processor, coupled to the image sensor, configured for calculating variations of brightness values of pixel units of the plurality of images, and for determining whether the object under test is a living body according to the variations;   wherein the processor is arranged to disable the physiological feature detection circuit when the object under test is determined as a non-living body.   
     
     
         16 . An electronic device, comprising:
 a physiological feature detection circuit;   an image sensor, configured for capturing a plurality of images of an object under test; and   a processor, coupled to the image sensor, configured for calculating variations of brightness values of pixel units of the plurality of images, and for determining whether the object under test is a living body according to the variations;   wherein the processor is arranged to stop outputting a physiological feature when the object under test is determined as a non-living body.